Have a look at the foolowing sentence:
Either some dogs or a fox_________ the farmer's chickens.
The teacher's book gives a. is attacking as the correct answer but I feel I can't explain why. And what is wrong with answer b? I can't find anything that might imply the use either of present progressive or the present perfect tense.
Thank you in advance!!!
Present perfect is only likely if you see the result of what happened.
Even If the speaker/writer were a witness to the attack, his use of the continuous form would stop at the end of the attack. After that point, the present perfect would be very logical.
Last edited by MikeNewYork; 23-Nov-2006 at 01:11.